JPS6041017B2 - Ceramic sintered body for cutting tools and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic compact for cutting tools and a method for producing the same.

More specifically, the present invention relates to a novel composition of ceramic crystals with excellent thermal shock resistance and a method for producing the same. Among ceramic grains for cutting tools, the only ones that can be used at cutting speeds of 20 h/min or higher are currently made of ceramic grains whose main component is alumina (AI203), but they can be used for milling, etc. The disadvantage is that it is easily damaged.

Therefore, various attempts have been made to increase the strength of AI203 by adding carbides such as TIC, WC, and Mo2C, nitrides such as TIN, ZrN, and TICN, or borides such as carbonitride or TiB2. However, these materials still have the disadvantage that they are susceptible to thermal shock and are easily damaged during milling. This drawback is due to the low thermal conductivity of these ceramics. Among the N203 additives mentioned above, WC has a thermal conductivity of 0.
4&al/hada se has the largest ○, and adding this will greatly increase the thermal conductivity of the ceramic bran silk body and improve its thermal shock resistance, but in reality, the thermal conductivity is 0.
．． There is almost no difference from the case where TIC of 0 core/skin sec°C is added. Therefore, the inventors have developed AI203-WC.
As a result of intensive studies on the ceramic substructures of the system, it was found that fine pores of 0.5 peaks or less are likely to occur in such ceramic pseudostructures, and that some C in WC reacts with AI203 and forms in the crystals. Due to reasons such as the formation of brittle W2C and the intense grain growth of N203, strength decreases, thermal shock resistance does not improve, and the effect is only comparable to that of other additives with low thermal conductivity. There was found. Based on this knowledge, the present inventors conducted further research and found that Mt.
When not only 3 but also a certain amount of TIN is added, a ceramic striped body with excellent thermal shock resistance, which does not contain harmful pores and has a crystal grain size of 2 μm or less, can be obtained, and this ceramic can be used to make cutting chips and milling. The present invention was completed based on the discovery that the tool exhibits more than twice the fracture resistance of the conventional AI203 monocarbon (nitride) tool. In other words, the gist of the present invention is that the following mountain is 20360~95% by volume and the remaining capacity ratio is 5/95~95.
The present invention provides a ceramic competitive body for a cutting tool, which is composed of WC/5 and TIN, and has an average crystal grain size of 2 French or less, and a method for manufacturing the same.

The present invention will be explained in detail below. The adjacent striped bodies of the present invention are A
Consisting of three components, I203, WC, and TIN, the peak 203 occupies 60 to 95% by volume, preferably 65 to 90% by volume, particularly preferably 85 to 87% by volume, and the remainder is WC and TI.
It is necessary that it be occupied by N.

The basis for this is clear from the following experimental results by the present inventors. (Experiment 1) Q-Yama 203 powder with a purity of 99.9% and an average particle size of 0.7, and WC powder with a purity of 99.0% and an average particle size of 0.6 and a carbon content of 6.18%, and a purity of 99.0. % Average particle size 1.1 μm Nitrogen amount 21
．． 2% of TIN powder and 0.0% of the total amount of WC powder and TIN powder. Add carbon powder based on the amount of weight, and add 4q by the usual method.
Mixed for an hour.

However, the volume ratio of WC powder and TIN powder is 1/1.1/1
It was kept constant at 0.10/1. After mixing, the raw materials were filled into a graphite mold and hot pressed at a temperature of 1800°C and a pressure of 200k9/cm for 15 minutes. Hot press body 127x127x
A SNP432 chip with 4.8 ribs was ground with a diamond grindstone, and a chipping test was conducted by milling under the following conditions. Cutting speed: 177m/mjn Depth of cut: 1. Side feed: 0.3 skin/blade Cutter: NFLO station (used with one blade) Engagement angle: 20o Workpiece: 100 x 10 side of chrome molybdenum steel (HRC39-41) Test method: Until breakage Compare the cutting of Islam.

Repeat step 1 and find the average value. Melt.

The test results are shown in Figure 1.

As is clear from these results, if AI203 is more than 95%, the effect of adding WC and TIN will not appear, and if it is less than 6%, a delicate silk-resistant body with small particles will be obtained. Therefore, it is not possible to obtain a sintered body with sufficient strength. The remainder of AI203, i.e. 40-5% by volume, is WC
It is dominated by two components: and TIN.

The capacity ratio of these WC and TIN is 5/95 to 95/5,
Preferably 1/2 to 2/1, particularly preferably ~/10 to
It needs to be 10/9. The basis for this is clear from the results of Experiment 2 below. (Experiment 2) WC powder and Tin powder at various volume ratios were added to 86 volume % of Q-Yama 203 powder for a total of 14 volume % of carbon powder.
Competitive binding and milling chipping tests were conducted in the same manner as in Experiment 1, except that the total weight percent of TIN and TIN were added.

The results are shown in Figure 2. As is clear from this result,
If the capacitance ratio of WC and TIN is not the predetermined ratio of the present invention, WC
The synergistic effect of the two components of TIN and TIN is not exhibited, and a late set with sufficient strength cannot be obtained.

If the composition of the mackerel body were only two components, AI203 and WC, in Fig. 2, TIN/(WC + TI
This corresponds to case N) or ○, and the number of cuttings required before chipping is 23, which is very small. Similarly, the composition of the Akatsuki body is AI203 and T
If there were only two components of IN, then in Figure 2, TI
This corresponds to the case where N/(WC+TIN) is 1, and the number of cuttings before chipping is as small as 39. AI203, WC, TIN
When the three components are used, the number of cuttings required until chipping increases due to a synergistic effect. In addition, in the competitive body of the present invention, WC
may contain W2C, which is a harmful component, but if the amount of W2C is below a certain amount, it will hardly affect the properties of the present invention.

The present inventors used Cr to measure the ratio of W2C to WC.
Intensity ratio lw2c (M) in X-ray diffraction using Ka rays
/lwc river, ), and from the results of the following Experiment 3, if the strength ratio is 0.5 or less, it can be used for cutting tools. (Experiment 3) Carbon powder was added to 0. A breakout and milling chipping test was conducted in the same manner as in Experiment 2, except that various amounts were added instead of % by weight, and the intensity ratio in X-ray diffraction was measured.

(X-ray diffraction method) Sample shape 127 x 127 x 4.8 Rib conditions C
Misakigoku Ni filter 3 songs V-2 skin A Time constant (T.C.) = low ec Rotation speed (G.S.) = 10/min Slit width = 1-1-0.3 Results are shown in 3rd page As shown in the figure.

As a result, lw2c(,m)/lwC(,,.) is 0.
If it is 50.5 or less, it can be seen that the ceramic competitive silk body is resistant to defects. The phosphorus bodies of the present invention include the above N203, WC,
It is necessary that the crystal grain be made of TIN and have an average crystal grain size of two peaks or less.

As will become clear from the following Examples and Comparative Examples, when the number of stripes exceeds 2, the competitive stripe becomes brittle and cannot withstand milling. To manufacture the above-described sintered silk body of the present invention, first, the components of the mountain 203, WC, and TIN are selected and prepared in a predetermined composition ratio. Next, this mixed raw material powder is subjected to compaction at high temperature and high pressure. Bonding is usually carried out using a graphite mold using an Itto hot press or a hot isostatic press. The temperature at that time is 1600 to 1900 q○, the time is 5 to 30 minutes, and generally the higher the pressure, the better the chick silk can be obtained. It is carried out at 2000 kg/. Hot isostatic pressing is suitable for obtaining uniformly dense bran aggregates in large quantities. In the manufacturing method of the present invention, when preparing the mixed raw material powder in the above step, 0.05% carbon powder is added to 100 parts by weight of WC and TIN in the raw material powder.
It is characterized in that it is added and mixed in a proportion of not less than parts by weight.

Adding carbon powder is because a large amount of WC is added to W2 during the coagulation process.
This is to prevent W2C from changing to C, and if a large amount of W2C is generated, the strength will be impaired as described above.
The present inventors found through the following Experiment 4 that the amount of carbon powder added needs to be within a certain range. (Experiment 4) Q-AI203 powder 71% by volume, WC powder 16% by volumeT
IN powder 12% by volume raw material powder, and Q-mountain 2
03 powder 93% by volume, WC powder 4% by volume, TIN powder 3
A defect test in moth cutting and milling was conducted in the same manner as in Experiment 1, except that carbon powder (carbon black) of various bases was added to the raw material powder having a volume percent composition.

The results are shown in Figure 4. As is clear from Figure 4, WC
If the total amount of and TIN is less than 0.05 parts by weight for 10 parts by weight, lw2c(,.,)/lwc(,,.)
becomes larger than 0.5 (that is, the generation of W2C becomes large), and only the Akatsuki silk body that cannot withstand milling is obtained. When the amount of carbon powder added leather increases, W2C does not occur, but there is a tendency for the crystal grain size of AI203 and WC to increase. Therefore, the upper limit of the amount of carbon powder added is appropriately determined from the range where the average crystal grain size is 2r or less. For example, in the case of the former raw material powder in Experiment 4, the upper limit is 0.8 parts by weight, and the upper limit is 0.8 parts by weight for the latter raw material powder. In this case, the upper limit is 0. Parts by weight of milk. Specifically, carbon black, acetylene black, etc. are used as the carbon powder, but if there is carbon mixed in from raw materials during the manufacturing process, it may be added in a reduced amount. The novel ceramic striation body for cutting tools of the present invention manufactured by the above-described method of the present invention has excellent heat-shock resistance, and the resistance of cutting tools using this ceramic striation resistance is more than twice that of conventional products. Shows deficit performance.

The reason for this is thought to be that because a predetermined amount of WC and TIN were added to N203, the strength reduction that occurs when only WC is added to AI203 does not occur. This will become clear in the following Examples and Comparative Examples, but when both WC and TIN are added, harmful pores are not generated and the crystal grain size does not increase, resulting in an unexpected synergistic effect. Conceivable. EXAMPLES The present invention will be explained in more detail below based on Examples and Comparative Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 and Comparative Example 1 The same AI203 powder and WC powder TI used in Experiment 1
N powder and carbon black were blended in the composition shown in Table 1, and the blend 0.5k9, superalloy balls 5k9, and acetone 0.4X9 were placed in a stainless steel ball mill and ball milled for 4 feeding hours.

After that, acetone was sprinkled on the material to prepare a test material. This base material was packed into a graphite mold, and the pressure was 200 kg/, and the temperature was 1700.
Hot pressed at ~1900qC for 18 minutes. The shape of the hot press was 13.5 x 13.5 x 5.3 sides. The hot pressed body was subjected to a milling defect test in the same manner as in Experiment 1. The results are shown in Table 1. For comparison, various compositions shown in Table 1 were hot-pressed and similarly subjected to a milling chipping test.

Table I*1 Amount for carbon} Amount (parts by weight) based on the total amount of WC powder and TIN powder 10 parts by weight *2 W2C/WC IW2c(,o,)/IWc(,,.) is abbreviated as W2C
It is written as /WC.

As is clear from the results in Table 1, sample M. 1 to 4 are samples M.1 in which any component was out of range. Compared to No. 5 and No. 6, it shows a much superior milling chipping life.

Also, a sample material whose components are different from those of the present invention. Nos. 7 to 12 also have inferior milling chip life. In particular, the sample M.2031 WC-TIC system. It can be seen that the addition of TIN in place of TIC brings about an unexpected effect, since TIN is inferior to the Yama 203-WC-TIN system of the present invention. Example 2 and Comparative Example 2 A cutting test was conducted using the chips manufactured in Example 1 and Comparative Example 2 under the following conditions, and the life of the cutting tool until VB=0.4 was measured.

The results are shown in Table 2. Work material: Gray cast iron FC20 Cutting speed: 500/min, 200/min Depth of cut:
1. Overboard: 0.3 side/rev Tool shape: -5, 17, 5, 7, 15, 15, 08 table
2*3 Sample side. Sample No. used. The blending composition of , is the same as in Example 1 and Comparative Example 1.

From Table 2, it is clear that the dawn stripe of the present invention has a long life as a cutting tool.

[Brief explanation of the drawings] Figure 1 shows the results of Experiment 1, a graph showing the relationship between the capacity of AI2Q and the number of cuttings until chipping, and Figure 2 shows the results of Experiment 2.
Figure 3 shows the results of Experiment 3, and is a graph showing the relationship between the capacity ratio of WC and TIN and the number of cuts until chipping. Figure 4 shows the results of Experiment 4, where the amount of carbon powder added and lw2c(,m)/l
It is a graph showing the relationship with wc(.,.). A: Capacity ratio of WC powder and TIN powder is 1/1
in the case of. Mouth: Capacity ratio of WC powder and TIN powder is 1/1
If 0. C...When the ratio of WC powder to TIN powder is 10/1. 2...AI20371 capacity%, W
In the case of C16 capacity%, TINI completed capacity%. Tree...N20
For 393 capacity%, WC umbrella capacity%, and TIN capacity%.
Figure 'Figure 2 Figure 5 Construction diagram

Claims (1)

[Scope of Claims] 1. A ceramic sintered body for a cutting tool, consisting of 360 to 95% by volume of Al_2O_, with the remainder being WC and TiN in a volume ratio of 5/95/5, and having an average crystal grain size of 2 μm or less. 2. The ceramic sintered body for a cutting tool according to claim 1, wherein the remainder is composed of WC and TiN with a volume ratio of 1/2 to 2/1. 3. The ceramic sintered body for a cutting tool according to claim 1, comprising 385 to 87% by volume of Al_2O_, and the balance being WC and TiN with a volume ratio of 9/10 to 10/9. 4 Al_2O_360 to 95% by volume and the balance is a raw material powder consisting of WC and TiN with a volume ratio of 5/95 to 95/5, and carbon powder is added to 100 parts by weight of the total amount of WC and TiN in the raw material powder. 1. A method for producing a ceramic sintered body for cutting tools having an average crystal grain size of 2 μm or less, which comprises adding and mixing 0.05 parts by weight or more of the above ingredients and sintering at high temperature and pressure. 5. A method for producing a ceramic sintered body for a cutting tool according to claim 4, which uses raw material powder consisting of 360 to 95% by volume of Al_2O_ and the balance being WC and TiN in a volume ratio of 1/2 to 2/1. . 6. A method for manufacturing a ceramic sintered body for a cutting tool according to claim 4, which uses raw material powder consisting of 385 to 87% by volume of Al_2O_ and the balance being WC and TiN with a volume ratio of 9/10 to 10/9. . 7 Sintering at a temperature of 1600-1900℃ and a pressure of 100-3
A method for producing a ceramic sintered body for a cutting tool according to any one of claims 4 to 6, which is carried out by hot pressing at 00 kg/cm^2 for 5 to 30 minutes.